I consider myself fortunate to have had high school teachers who not
only allowed, but encouraged, the use of graphing calculators in the
classroom. In fact, I've been using a graphing calculator since my
eighth-grade geometry class (I won't tell you how long ago that was,
but TI-83 was the new kid on the block). As I considered my
experiences with the graphing calculator, I was able to find a moment
when I used the calculator for each of the identified roles. For
example, I used the calculator to evaluate expressions (didn't
everyone?), check my answers (especially when I was working with
systems of equations or graphing), gather data on a bouncing ball's
height (this use is restricted to my college and teaching
experiences), visualize and interpret equations and data, and I think
perhaps slightly as a transformational tool (I remember my pre-
calculus teacher describing how in the past when she taught regression
she had to focus on computations and was restricted to linear
regression, but with the calculator we would be able to explore
exponential and quadratic regression as well and determine which best
described our data). Still, I probably used it primarily as a
computational, visualizing, and checking tool. However, I don't think
that my use of the graphing calculator was as mathematically rich as
was described in the article. Although my teachers encouraged us to
explore with the graphing calculator and not to accept it as an
authority, they never followed-up our explorations with a discussion.
I think that the absence of a mathematical discussion weakened the use
of the calculator in the classroom.
A wise college professor once told me that the answer to all questions
is "It depends" (Dr. Grimshaw, BYU Statistics). This brings me to the
second question posed: do you think that some roles should be more
encouraged or less encouraged in the mathematics classroom? I think
that all roles should be encouraged. Let me qualify that statement
with the following explanation. I think that within each role there
are varying degrees of mathematical thinking participated in by the
student. For example, in the visualizing role, the calculator can be
used to graph equations or it can be used to compare and contrast
different modes of function representations that can be used to solve
systems of equations. I think that the former use is qualitatively
different from the rich mathematical potential of the later. I also
think that the different roles of the calculator accomplish different
things mathematically. For example, the role of the calculator as a
computational tool seems to allow more opportunities for students to
develop their number sense, whereas the data collection and analysis
role seems to provide students with an opportunity to explore physical
phenomena mathematically. Thus I think that all roles should be
encouraged, with careful considerations concerning the depth and type
of mathematics the teacher wants the students to learn.